Electronic Private Automatic Branch Exchange (EPABX)

A private branch exchange (PBX) is a telephone exchange serving a business or office, as opposed to one common carrier or telephone company operating for many businesses or for the general public.

One main advantage of an EPABX is the ability to use 2 or more telephone lines among 8 or more users. More sophisticated EPABX machines are capable of handling 12 lines and distributing them to even 100 or more users. These systems are scalable as your business grows starting with 2 lines and add on more lines needed.  Other features often include hold music, fine me/follow me, mobile integration and call recording.

The PBX is owned and operated by the enterprise rather than the telephone company (which may be a supplier or service provider, however). Private branch exchanges used analog technology originally. Today, PBXs use digital technology (digital signals are converted to analog for outside calls on the local loop using plain old telephone service (POTS ).

A PBX includes:

Telephone trunk (multiple phone) lines that terminate at the PBX
A computer with memory that manages the switching of the calls within the PBX and in and out of it
The network of lines within the PBX
A console or switchboard for a human operator (optional)

In some situations, alternatives to a PBX include centrex service (in which a pool of lines are rented at the phone company’s central office), key telephone systems, and, for very small enterprises, primary rate Integrated Services Digital Network (ISDN).